In the field of crystalline silicon solar cell production, in order to enhance the absorption of solar light, a texturization of the front surface of the solar cell is performed. This improves light trapping properties by reducing reflection losses, thereby improving the external quantum efficiency and thus the energy conversion efficiency of the cell. The quality of this texturization is crucial for the performances of the solar cell. In particular, size and uniformity of the textured structures are key parameters influencing said performances. Typically, these textured structures have a pyramidal shape and their homogeneous distribution in size and space is wished. Prior to this texturizing, one or more preparatory steps are typically performed on the as-cut crystalline wafer received from the wafering company. These preparatory steps are necessary because the surface of the wafer is highly contaminated with traces of the dicing process like, slurry, metals, organic impurities, etc. One important preparatory step is the removal of the saw damage (Saw Damage Removal, SDR) typically performed just before texturizing. SDR is typically performed by using a potassium or sodium hydroxide solution at a concentration of from 20% to 40% by weight.
US 2011/0111548 A1 attempted improving the quality of the surface texturizing by introducing a pre-cleaning step prior to a typical SDR step. This pre-cleaning step consisted in applying ozonated deionized water to the as-cut surface of the crystalline silicon substrate to remove surface contaminants.
In US 2011/0111548 A1, depending on the sample measured, the obtained reflectance (averaged from 9 points on the sample) was within the range 9.05 to 9.47% at 950 nm. This corresponds to a reflectance of about 9.3% at 950 nm (average from 8 different samples). This in turn corresponds to a reflectance in excess of 10% if measured at 700 nm. Again depending on the sample measured, the standard deviation of the 9 reflectance measurements performed on a sample was between 0.7 and 2.1% in absolute value, i.e. between 0.7 and 2.2% in relative value (see FIGS. 4 and 5 of US 2011/0111548 A1).